Interference is becoming of greater significance, both intentional and unintentional as technology becomes more advanced, available and as the amount of traffic increases. Interference on a broadcast system can have significant impact potentially blocking and denying the service.
Document US2010/0265116 describes an earth receiving station comprising:                an earth receiving station that is configured to receive an input signal and produce therefrom a baseband signal;        a earth receiving station that is configured to detect a jamming signal in the input signal at a jamming frequency;        a replica signal generator that is configured to generate a replica jamming signal at the jamming frequency, and        a combiner that is configured to combine the input signal and the replica jamming signal so as to substantially cancel effects of the jamming signal on the baseband signal.        
Consequently, according to this document, the earth receiving station is provided with an anti-jamming system comprising the replica signal generator and the combiner. This anti-jamming signal enables to decrease the effect of a jamming signal on the input signal received by the earth receiving station. However, according to this document, each earth receiving station has to be provided with an anti-jamming system to be “protected” against the jamming signals. Consequently, the anti-jamming system is integrated to each earth receiving station, which is very expensive. Besides, the anti-jamming system is configured according to the earth receiving station inside which it is integrated, which is very complex when there are a wide range of earth receiving station categories. Moreover, the anti-jamming system of this document enables to diminish the impact of the interference on the earth receiving station, but the interference has still an impact on the power of the earth receiving station signal.
US2010/0289688 describes a method of providing a signal 180° out of phase with a jamming signal such that the effect of the jamming signal is cancelled or substantially reduced at the earth receiving station level. This method and device is applied to a military environment in which personnel communicate using Talk While You Jam TWYJ radios in which the radios are required to jam both ‘friendly’ jamming signal and enemy signals. The radios of this document are intended to be provided with a database of known enemy jamming waveforms and have signal processing components that enable the radios to detect and classify received enemy jamming signals. The processing is performed at the earth receiving station such that it is able to decode information from a second signal received on the same channel as a known waveform. When in receive mode the radio emits a jamming cancellation signal. However, the arrangement described in this document could not be applied to a satellite broadcast system in which the signals are transmitted to a wide coverage region.
Other methods of the prior art suggests to provide satellites with on-board anti-jamming systems. However, such systems are very expensive, not applicable to the satellites already in operation and once again they must be adapted to each type of satellite inside which they are integrated.
More generally, the anti-jamming systems of the prior art focus on mitigation of Adjacent Satellite Interference through multiple earth receiving stations and signal processing techniques.